Electric system for recording and reproducing sound



May 10, 1932. E. H. HANSEN ELECTRIC SYSTEM FOR RECORDING AND REPRODUCING Filed Nov. 25. 1927 sets-Sheet 1 AAAAAAA [III IN V EN TOR.

May 10, 1932;

ELECTRIC SYSTEM FOR RECORDING AND REPRODUCING SOUND E. H. HANSEN .Filed NOV. 25'. 1927 2 Sheets-Sheet 2 AUE/f- MOTOR 4 m TOR 2 as ll4 L000 SPEAKER Patented May 10, 1932 Urrs STATES PAT NT-creme EDMUND H. HANSEN, or NEW YORK, N. Y.

ELECTRIC .sYsrInvr roa nnconnmeaun REPRODUCING scum)- Application filed November 25, 192% Serial No. 235,526.

This invention has reference to a system a and apparatus for. making a photographic record of sound waves, and the reproduction of sound waves from the record so made,

The object of my invention is to provide an electrically operated means for recording.

-2 construction, combination, location, and relative arrangement of parts, all of which will be more fully shown hereinafter, as set forth by the accompanying drawings, specifications, and finally pointed out in the appended claims.

Referring tothe drawings, Figure 1 is a diagrammatic view of. the mechanism, and electrical circuits utilized in recording. a

Figure 2 is a diagrammatic view of the mechanism, and the electrical circuits utilized in the reproduction of sound from therecord so made in Figure 1'. Q a

Figure 3 illustrates the mechano-optical arrangement of the rotating head used in both recording and reproduction.

Figure a is a view of the sound record obtained when utilizing a recording system as shown by Figure 1. 2

Referring to the drawings, in Figure 1 the innneral 1 indicates a source of sound such as a tuning fork, although it is intended'that the term sound shall'cover all vibrations of audible frequencies, the sound to be recorded is intercepted by means of a .microphone preferably of the electrostatic type as'indicated by the numeral 2.' Micro-' phone 2 is in a circuit consisting of a resistor 3, and battery source 4, sound waves impinging on the movable plate of microphone 2 Another object of my inventionjis to prois energized from positive terminal of batresistor 28.

j triode.

cause :a displacement proportionate to a fre quency amplitude variation in the sound wave thereby causing a resultant potential change in the resistor 3, and a like change in potential on grid 7 of triode. A capacity 5 is utilized in coupling resistor 3 and grid 7,

the circuit being completed by connecting the negative terminalof battery-source 4 to filament 80f triode, and resistor 6is placed lin circuitbetween grid-7 and filament 8 for regulating grid voltages. r

Anode 11 is in circuit with resistor 12 to which is excited by battery 10 and controlled by a variable resistorfi Signals ongrid 7; are thus amplified in the conventional ther inionic manner andrpotential changes in resistor112 are introduced togrid 17 of the second triode through a capacity "13, and a connection made from filament 8 of first-triode to filament 16 of second triode. Resistor 14 is connected to negative terminal of biasing Filament 16 isexcited by a battery source 19 a positive terminal of battery source l, and from negative terminal to filament 8 of triode and regulated by a variable resistor 20.

Anode 18 of second triode is in circuit with primary 21 of a coupling transformer and tery source 4,.the negative terminal of which is connected to filament 16; v v

A transfer of signal energy is made to secondary winding 22,,of coupling transformer, the upper leg'of which is connected with grid 25=of third triode. The lower leg is in cir:

cuit with negative terminal of biasingbat tery 23, thence from positive terminal of hiasing battery 23 to filament 24 of the third triode, this filament is energized from a battery source 27 andfis regulated by a variable actor coil 29, positive terminal of battery source 30, and thence from negative terminal toresistor 28, and filament 24 of thethird A glow tube 33 is in circuit with resistor 32 and battery source 30, current in the glow tube 33 being regulated by the values of .re-

Anode 26 is in circuit with resistor 32 and potential of battery source 30.

. 5 tery source'51', energizing winding'50 through A value is obtained whereby the'intensity of light emitted from glow tube 33 will cause an exposure on the photographic film equal to a mid point on the characteristic exposure density curve of the film used. In this con- "dition the alternating current component flowing in anode circuit of third triode and consisting of anode 26, reactor 29 and battery source 30, is connected through coupling capacity 31, and negative .terminal of battery source 30 to terminal of glow tube 33,

and will modulate and vary the intensity" of glow tube 33 proportionately to the frequency amplitude displacement ofmicrophone 2.,

Included in and a part of the light tight box 62" is a drive motor 44 energized from a source of power 68, and regulated through avariable resistor 67, and having a shaft common with an alternator 45,col1ector rings '46, a-mercury balance-wheel'43, and gear 42. Alternator base frequencyequal to that of electrically driven tuningfork 47 when.

motor 44 'isrotating at-its optimum speed. Tuning fork 47 is driven by means of a batcontacts 49, outputof alternator 45 passing through collector rings 46 to control contact which engage the sprocket holes of motion picture film 5'Twhich is stored on reel 56,'and

threaded past guide'riollers 58and 59, ex

posure mask 60, guideframe 61, over sprocket 54 and then is wound'upon take up reel 64.

, Take up reel64 'is'rotated by means of power transmitted from pulley 66 attached to sprocket 54, flexible belt 63 and pulley65 which is'attached to and apart of takeup e l. .v a .i i

Gear V41'is' also used to drive gear 41 by means of a connecting gear train, and motion is imparted to the shaft 40, bevel gears 39,

"shaft 37, and the opticalhead. A housing 38 is attached to the'lig'ht tight'box 62, and

has anopening thereto. Shaft 37 passes through a bearing formed inhousi'ng38, and

carries the optical head consisting of lower support 34, optical tubes 36 and upper sup port 35. The glow tube 33-rests in a support formed on housing ;38, and upper support 35 of optical head rotates around base ofglow tube support.

Figure 3 isa' view looking with reference-to exposure mask, 60, glow glow-tube rays.

down on s a calhead and shows position of optical head tube 33 and housing 38. Referring again to Figure 1 it will be observed that glow tube 33 occupies a fixed position relative to the optical head which, as it rotates, brings in successively a plurality of optical systems each consisting of a tube 36, condensing lens 71, slit 70, and focusing lens 69.

It will be observed that as motion from the motor 44, rotates the sprocket 54, drawing film from storage reel 56 past the exposure mask and thence, by means of take up pulley 66, belt 63, and pulley 65, on to the take up reel 64, optical head rotates around glow lamp :33 in such a manner as to sweep alpath of exposure of unit width from side to side of the recording film. It will be further'observed that the-multiple optical system isso-arranged as to provide a continuous rotary motion to the rays of the glow tube 33, as focused by means of the optical sysiBDI'PlGVlOUSlY' described, and which, upon passing through the exposure mask 60, act

uponthe light sensitive film being drawn past-therotating optical head. That is-to say, the filmis causedto travel continuously relatively to'the exposuremask, at a rightangle to, or perpendicularly to, the plane in which the optical system travels and the rays of the glow-tube. Or, otherwise stated, the

film travels in a path tangential to the path of rotation of the optical system and of the Thus helical striations of audible frequencies, or sound vibrations, are

recordedonjthe film; The numberiof optical systems employed in the' optical head is dependent upon the width ofthe film used and the radial distance from the centcr of glow tube 33 tov the film. V

I have found it'desirable to use standard motion picture negative which having a working width of one inch, and a 45 degree spacing betweenoptical systems, eachhaving an optical radius of one and a quarter inches approximately from center of glowv tube to recording film. Referring to Figure 4 a representation of the exposed-and developed film I g It will be ob served that instead of the conventional verinade in this manner-isshown;

tical strip of sound striations ahelical record is made" permitting a linear speed approximately ten times greater than the conventionfal motion used in recording sound on film.

Roughly one hundred'fee't of film usedin this manner is equal to one thousand feet where V a single vertical striaticpath is employed.

I have found it extremely difiicultto photograph an image of a slit smaller than one thousandth of an. inch in thickness, and it will be noted'that at a frequency of eight thousand cycles which is necessary for high quality recording, 'andalinear film speed of ninety feet aminute there is available a total path length of twenty-two mills'when recording by my systemas against two and two tenths; of mill when using the conventional vertical path method. This permits all of the complex waveform to be fully recorded instead of a few low frequency fundamentals.

the photographic processes employed beingv well known to the art. m

Figure 2is a diagrammatic drawing of the system and apparatus required for the reproduction of a photographic record of sound made in the manner previously described. A housing 104 contains the driving motor whose shaft is common with alternator 89, collector rings 90, mercury balance wheel 88 and drive gear 84. Power is supplied motor 85 from a source 87, and'regulated by a variable resistor 86, by this means the motor speed is regulated to a point at which the alternator 89 will have a frequency sufliciently high that any line volt-age variation will not reduce frequency of alternator 89 to less than that of the electrically driven tuning fork 97. Fork 97 is actuated by battery source ex citing winding 93 the circuit being closed by means of a'contact 94, the output of alternator 89 being taken from collector rings 90 and shunted through fork prong contact- -ors at 92. This control of alternator frequency will react'through common shaft-to drive gearing 84, and will permit synchronous speed with respect to the recording mechanism if the control forks in each case have similar freque'nciesof vibration.

Driving gear 84 is-in mesh with gear96 which cause a rotary motion to be imparted to shaft 97, and thence through bevel gears 98 to film driving sprocket 100. ,The photographic record of sound 57 is storedon reel and threaded past the guide rollers 106,

107, and between apertured mask 108, and guide mask 109, thence it is engaged by the teeth of driving sprocket 100 and stored on take up reel 103 which is rotated by means of pulley 99, mounted'on and'a partof driving sprocket 100, and driving pulley 102 through a flexible belting 101. p

Driving gear 84 is also in mesh with a gear train which drives gear 83, andthereby imparts motion to shaft 82, bevel gears81,-shaftpreviously described in the recording system; v

A source of light 72, which in practice is of the concentrated filament incandescent type, is heated from a battery source 73 and the temperature is-regulated by means of a variable resistor 74. The condensinglens 71 concentrates maximum light intensityin the slit opening 7 O, which is of a unit size previously described, the image of this slit'70 is focused through the faperture mask 108, and thence through film57, opening in guide mask 109 and. on to and through condensing lens 113, which refocuses this now modulated light ray on to photo electric cell 114. The 3- purpose and size of condensing lens 113 being such that regardless of the position of light ray onfilm 57, the light ray will always fall on the same It-will be noted that as film 57 isdrawn over sprocket 100, in a vertical movement, analyzing optical head is interlocked in a horizontal rotation, and throws a light ray of unit width and length through film 57 in it such a manner as to scan the sound record thereon, and causlng said llght ray .tobel modulated according to thedensity,'and frequency,'of the striatic structure.

This modulated light ray falling on photo electric cell 114 causes liberation of negative electrons resulting in a flow ofelectrical cur-,

rents in a circuit consisting of photo cell 114,

battery source 116 and resistor 115. Grid ,119

of triode'is coupled to this circuit at the point between, photo cell 114 and resistor through a capacitance 117. Control circuit is completed by connecting filament .120 of triode tonegative terminal of battery source 116. Resistor 118 isplaced in this grid 7' control circuit in theconventionalmanner for the purpose of regulating grid charges.

Filament 120 of triodeis heated from a battery source 123 thetemperature being controlled by a variable resistor 124, andafixed resistor is added in the opposite leg-of filament at a point 122 for the purpose of providing a negative biasing potential; Anode 1210f triode is energized through primary winding 126 of coupling transformer froma battery source 125. Energy from secondary Winding 1270f coupling transformer'is fed intoan amplifier loud-speaker system 128 which may be in and of any conventional form well known-to the art.

From the above detailed description'itis obvious thatmy system is capable of recording any sound and vibration of audio fre quencies as well as reproducing the same in a clear and natural manner. Itis' apparent that various changes may be made in the system departing in anywise from the spirit of the invention as set forth in'the appended claims.

portion of photo electric cell ioa terr'elated supporting and activating means i for the-film and optical head for causing'the two to travelin planes at a-right-angle to each. other at a predetermined point.

- V 2. Apparatus for recording sound, having, in combination, a multiple optical head havingiradial optical systems, audio frequency receivingmeans connected to said head, a

determined point.

.light-sensitivefi-lm, and interrelated supporting and activating means for thefilm and optical head for producing upon the film a parallel, striatic structure of helical formationby said radial opticalsy'stems.

3. Apparatus for recordingandreproducing sound having, in combination, .a multiple optical system, audiofrequency receiving and transmitting meansassociated with said head, a film,i-and interrelated supporting and activating .means for the film and optical system for causing the optical system to rotate in a horizontalplane and the film to-travel in a vertical plane-relative to said systemat a pre- 4. Apparatus :for recording and reproducing-soundhaving, in combination, a multiple optical headwhaving'radial optical systems,

' audio frequency receiving and transmitting means,a film adapted'to travel in a plane perpendicular "to the plane of said-head, and" interrelated supporting vand activating means for-sthe film andoptical head, and alight sourcelocated axially in said head-and con- 7 centrically'locate'd in the opticalsystem arsaid radial optical systems;

ranged to transmit light'to'said film through 5.. Apparatus for recording andreproducing sound having, in combination, a multiple optical system,- audio frequency receiving and -transmitting means, a film adapted to travel in a plane perpendicular to the plane of said head, and interrelated supporting and activating'means forthe film and optical system and including differential gearing for; causv in the film travelxto'be appreciably slower than that of the system; w

6. An apparatus for. recording and reproducing audio frequency comprising a shaft carrying a motor, an optical system arranged in a 'horizontalplane; a film'and means-for causing it to travelrelatively to the optical system at an angle to the latter; an exposure mask and means cooperating,therewith -to guide the filmrelatively to the optical system; and driving means betweenthe motor shaft,

the film traversing'means, and the optical system including differential gearing for musing-the film and 1 optical system .to travel at the desired predetermined relative speeds.

7-. Apparatus'for reproducing sound; having, in combination, -a.,multiple,, o tical head having radial optical systems, a lm having raphelicalqsound track of parallel istriations thereon, alight common to said radial optical systems adapted to transmit light through said striations, interactingsupporting and actuating means for the film and optical head for causing the film totravel perpendicularly relatively to the'systems, a photo, cell arranged to receive lighttransmitted through said striations, and an amplifier, and loudspeaker system circuit with said photo cell. Y c 8. An apparatus adapted'for both record 'ing, and f reproducing audio frequency comprising a shaft having-a motor and balance Wheel; means forener'gizing the motor; an exposure mask a film means for supporting and feeding the film-=includingmeans. for causing the film to travel a predetermined path relativelyto the mask a multiple optical head having radialoptical system's; means whereby-the optical, systemis causedto cast its lightr'ays perpendicularly upon the film; I

and means. activated by the shaft for driving the filmand optical system at speeds having a predetermined ratio. i i i c 9. An apparatus for recording andreproiducing audio frequency comprising a casing, a motor journaled in the casing; a rotatable" opticalhead mountedon the "casing in a plane perpendicular thereto an. exposure mask mounted within the casing and arranged adjacent the; circumference of theoptical head; afilm operating within thecasingperpendicularly tothe plan'e ofrotation of said head and having its delivery means atone end'of 'thecasing and itstake-up or storage imeanso at the other-end of the casing a guide frame cooperatively arranged adjacent the'exposure mask and operatingto guidethe filmfrom the delivery means to the storage means;

means for actuatingthe film; means :for actuating the optical; head and differential driving means between the 'motor and the said 'tWo actuating means whereby" the film and the head may betraversed relatively to each other at a predetermined speeds 10. An apparatus suchas defined'in claim .9- wherein-the film; and the optical head are arranged in cooperative relation for functional interaction, andthe driving means-of'differentialfch'aracter have aratiocausing the filmiand head to travel relatively'whereby to produce upon the film a'striatic structure of lielical formation.

11. An apparatus suchas defined in claim 9, having in combination therewith a circuit containing means. for recording audio frequencies; a second circuit containing means for reproducing audio'frequencies, and a photo-electric cell 7 arranged within .the 5 casing in said second circuit, and an amplifier and loudspeaker in series in said second cir- V cuit.

9 having in combination therewith a circuit containing means for reproducing audio frequencies; a second circuit containing means for IGCOIdlIlgaudio frequencies, acondensing lens in juxtaposition to the exposure mask and guide frame, a photo-electric cell in said reproducing circuit, and an amplifier and loudspeaker in series in said reproducing circuit.

13. In an apparatus for producing a transverse helical sound track having parallel striations upon a moving light sensitive film; an optical head having a plurality of optical systems arranged to rotate in a plane perpendicular to the plane of movement of said film and transversely of said film; and a sound modulated light source common to all of said optical systems.

I I. In an apparatus forproducinga transverse helical sound track upon a moving light sensitive film and transversely of said film;

an optical head having a plurality of optical systems arranged to rotate in a plane perpen dicular to the plane of movement of said film; means for synchronously rotating said head with respect with the movement of said film vand a sound modulated light source common to all of said optical systems.

15. In an apparatus for recording or reproducing sound; an optical head llELVlIlg a plurality of radial optical systems, eacli of said systems having a vertical light slit; a source of light common to said optical systems and means for moving said light slit transversely across the width of a vertically moving film to transmit light from said source to said film.

In witness whereof, I hereunto subscribe my name this 21st day of November, A. D.

E. H. HANSEN.

12. An apparatus such as defined in claim 

